My trainer has this schedule set up for me:
Monday: Personal Training Session (weight lifting and short cardio conditioning intervals)
Wednesday: Circuit Training Class (high intesnsity so some cardio mixed in)
Thursday: Strength Training (the areas I am not working with him that week, we switch it up every few weeks) and then 30 Min of Cardio, my choice on what I do but my goal is to burn over 300 calories which is fairly high intensity
Saturday: Circuit Training Class
Sunday: Optional cardio day (30-45 min)

I would say I spend 250-300 min a week in the gym and about half of that goes toward cardio. Some of it is mixed into classes though. Its a great combo for me I am toning from the strength training and also losing fat from the cardio. In about 5 weeks on this plan I have lost about an inch to 2 inches everywhere.

I personally get that endorphin rush I crave from cardio so I do a little 5 days a week. I have heavy cardio days 3 days a week (Spin class and elliptical) and light cardio days 2-3 days a week (usually running 3-4 miles).

My personal trainer recommended that I was doing too much cardio. Maybe. But I like it...and I get my strength training in there too.

Opinions seems to vary, I think you should whatever works for you and keeps you meeting your goals (within reason of course). When I first lost a lot of weight when I was a teen I started with 30 minutes a day and and I bumped it up to an hour. I have about the same amount of weight to lose (about 50lbs ) so I am going to try that route again and see how it works for me. Good luck!

I try to run 3 days a week and that is usually for 45 minutes or so. However, I walk ALOT and sometimes on the weekends I'll have walked 10 or 15 miles. Walking is not as intensive, but it slowly burns the calories and is a great way to relax and enjoy the outdoors.